There are Wikipedias (encyclopedias) in 300 languages, some of which contain more than one million articles.

There are Wiktionaries (dictionaries) in over 170 languages, some of which contain more than one million entries.

There are Wikibooks projects (textbooks) in over 120 languages, the largest of which contain more than 80,000 pages.

There are Wikiquote projects (quotations) in over 80 languages, the largest of which contain more than 30,000 pages.

There are Wikisource projects (source texts) in over 60 languages, the largest of which contain more than 600,000 pages. In addition, there is a multilingual "old" Wikisource wiki containing portals for languages that don't have their own separate domains yet (these are being migrated to the Incubator).

There are Wikinews projects (news articles) in over 30 languages, the largest of which contain more than 50,000 articles.

There are Wikiversity projects (educational materials) in more than 15 languages, the largest of which contain more than 40,000 pages.

There are Wikivoyage projects (travel guides) in more than 20 languages, the largest of which contain more than 25,000 pages.

There is one multilingual Wikimedia Commons project containing over 50 million files that can be used by all other Wikimedia projects.

There is one multilingual (but mostly in English) Wikispecies project containing over 600,000 entries about living things.

There is one multilingual Wikidata project containing over 50 million items that can be used by all language Wikimedia projects.

wmflabs.org wikis are not meant to host any original content (discussion, reports or whatever) but should only be considered as short-lived sandboxes. However, most of them don't give this very valuable information to most users.

Hosted within the production cluster, runs the current Wikimedia production branch of mediawiki. It's most useful for various tests of features before even applying them on other production wikis, like scripts or in upon testing other features.

Isolated clone of the production cluster, deployed directly from git. May be unstable. Users can test gadgets and scripts for compatibility with future releases. Wikis here are not accessible from anywhere, nor explained clearly, nor have an index or any navigation tool. Used to be deployment.wmflabs.org

List of canonical domain names owned by the Wikimedia Foundation, including some non-wikis ("While the Foundation may own many other domains for trademark, legal, or project/redirect reasons, there is only one small set which are considered to be the canonical set for our actual projects and content, which are subjected to higher standards.")

OpenStreetMap (OSM) is a collaborative project which is similar to a wiki in that people around the world contribute geographic data that can be used for many aspects related to mapping. Integration between OSM and WMF projects is close and much of their data can be reused within Wikimedia projects. See more details at mw:Maps.